Primer and multilayer coated article

ABSTRACT

A primer comprising a polymer which comprises copolymerized units of an UV absorber having an unsaturated double bond, and a multilayer coated article comprising a substrate, a coating of the primer and a surface coating. The coatings of the multilayer coated article exhibit excellent weathering-resistant adhesion to a substrate, and they improve the surface properties thereof, such as surface hardness, scuff resistance, wear resistance and surface gloss. Accordingly, the coatings can impart excellent durability to the article and inhibit weathering deterioration of the substrate.

TECHNICAL FIELD

The present invention relates to a coating used for improving thesurface properties such as surface hardness, scuff resistance, wearresistance and surface gloss, of a variety of substrates, a primer forimproving weathering-resistant adhesion to substrates, and a multilayercoated article.

BACKGROUND ART

Various coatings have been proposed to improve the surface properties,such as scuff resistance, wear resistance, surface hardness and surfacegloss, of various substrates. Many primers have also heretofore beenproposed to improve the adhesion between the coatings and thesubstrates.

Furthermore, for the purpose of preventing the substrates, the primercoatings or surface coatings from being subjected to deterioration andyellowing or peeling, caused by UV-rays in sunlight, during outdoor use,there have been made many attempts to add UV absorbers to thesubstrates, the surface coatings or the primer coatings.

For example, there have been the following disclosures: attempts to addUV absorbers to the substrates have been disclosed by Kokai (JapaneseUnexamined Patent Publication) Nos. 62-146951 and 1-247431; attempts toadd UV absorbers to the primer coatings have been disclosed by Kokai(Japanese Unexamined Patent Publication) Nos. 2-16129, 2-16048 and61-86259; and attempts to add UV absorbers to the surface coatings havebeen disclosed by Kokai (Japanese Unexamined Patent Publication) Nos.1-96266, 1-55307 and 63-83117.

DISCLOSURE OF INVENTION

However, in the prior art techniques as described above, the added UVabsorbers bleed when exposed outdoors for a long period of time, and asa result the coatings peel off, or the substrates and primer coatingsexhibit yellowing (discoloration). Accordingly, the addition of UVabsorbers cannot be considered as fundamentaly improving the weatheringresistance of the substrates.

The present invention is intended to solve the problems as describedabove, and has the following construction:

(1) A primer comprising a polymer which comprises copolymer units of anUV absorber having an unsaturated double bond; and

(2) A multilayer-coated article comprising a substrate, a primer coatingwhich comprises a polymer comprising copolymerized units of an UVabsorber having an unsaturated double bond on the substrate, and a hardcoating on the primer coating.

BEST MODE FOR CARRYING OUT THE INVENTION

Examples of the UV absorber having an unsaturated double bond in thepresent invention are UV absorbers of benzotriazole type, benzophenonetype, benzophenolate type, etc. There is no specific limitation on thefundamental structure of the UV absorbers, and UV absorbers having anunsaturated double bond are employed.

For example, examples of the benzophenone UV absorber having anunsaturated double bond include compounds having the followingstructure: ##STR1## wherein at least one of R¹, R², R³ and R⁴ is anorganic group having an unsaturated double bond (>C═C<), and the othersare each independently a substituent group such as an alkyl group, analkenyl group, an aralkyl group, an aryl group, an alkoxy group, anaralkoxy group, an allyloxy group, a hydroxy group, a halogeno group, asulfonic acid group, an ester of a sulfonic acid group, a carboxylicacid group, an ester of a carboxylic acid group, acid group and an esterof a phosphoric acid group and are not specifically restricted.

Furthermore, examples of the benzotriazole UV absorber having anunsaturated double bond include compounds having the followingstructure: ##STR2## wherein at least one of R⁵, R⁶ and R⁷ is an organicgroup having an unsaturated double bond, and the others are eachindependently a substituent group such as an alkyl group, an alkenylgroup, an aralkyl group, an aryl group, an alkoxy group, an aralkoxygroup, an allyloxy group, a hydroxy group, a halogeno group, a sulfonicacid group, an ester of a sulfonic acid group, a carboxylic acid group,an ester of a carboxylic acid group, a phosphoric acid group and anester of a phosphoric acid group and are not specifically restricted.

Still furthermore, examples of the phenyl benzoate UV absorber having anunsaturated double bond include compounds having the followingstructure: ##STR3## wherein at least one of R⁸ ˜R¹³ is an organic grouphaving an unsaturated double bond, and the others are each independentlya substituent group such as an alkyl group, an alkenyl group, an aralkylgroup, an aryl group, an alkoxy group, an aralkoxy group, an allyloxygroup, a hydroxy group, a halogeno group, a sulfonic acid group, anester of a sulfonic acid group, a carboxylic acid group, an ester of acarboxylic acid group, a phosphoric acid group and an ester a phosphoricacid group and are not specifically restricted.

Examples of the unsaturated double bond contained in the UV absorbers inthe present invention are a vinyl group, an allyl group, a vinylenegroup, a (meth)acryloyl group, etc. Though there is no specificlimitation on these groups, the (meth)acryloyl group being preferable inview of its reactivity.

The primer of the present invention comprises a polymer formed bycopolymerization of the UV-absorber having an unsaturated double bond asmentioned above with other monomer. Though there is no particularlimitation on the copolymer component other than the UV absorber in theprimer, those monomers having an unsaturated double bond or functionalgroup reactive with the unsaturated double bond of the UV absorber areused.

Those monomers which have an unsaturated double bond and formcopolymerized units of the primer are not specifically restricted tovinyl monomers or (meth)acrylic ester monomers. Examples of the monomersare various (meth)acrylate derivatives such as (meth)acrylic acid,methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate,hexyl (meth)acrylate, cyclohexyl (meth)acrylate, heptyl (meth)acrylate,octyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate,stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxy-propyl(meth)acrylate, methoxyoligoethylene glycol (meth)acrylate, glycidyl(meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylateand N,N-diethyl-aminoethyl (meth)acrylate, various polyfunctional(meth)acrylate derivatives such as ethylene glycol di(meth)acrylate,diethylene glycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate,1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate,neopentyl glycol di(meth)acrylate, trimethylolpropane (di/tri)(meth)acrylate, pentaerythritol (di/tri/tetra)(meth)acrylate andoligoethylene glycol di(meth)acrylate, various vinyl group-containingmonomers such as butadiene, isoprene, styrene, a styrene derivative anddivinylbenzene, and the like. Of these monomers, it is preferable to useone kind or at least two kinds of these monomers which improve theadhesion between various plastic substrates and surface coatings withoutimpairing the surface properties of the surface coatings, such assurface hardness and scuff resistance, corresponding to the substratesand the surface coatings. To realize good weathering-resistant adhesion,the primer is allowed to contain copolymerized units of the UV absorberpreferably in an amount of 0.1 to 20% by weight, more preferably 1 to10% by weight based on the entire monomers, though the amount depends onthe type of the substrate and the surface coating.

Examples of the monomer having a functional group capable of reactingwith the unsaturated double bond of the UV absorber are a hydroxy group,a thiol group, an imino group, etc. A monomer having an unsaturateddouble bond and a monomer having a functional group capable of reactingwith the unsaturated double bond of the UV absorber may both be used asthe copolymer component of the UV absorber.

Furthermore, the primer of the invention may also contain copolymerizedunits of a monomer other than those mentioned above. For example, it isa preferable embodiment to use an antioxidant monomer and a lightstabilizer monomer having an unsaturated double bond as the copolymercomponent for the purpose of further improving the weathering resistanceby their use with the UV absorber in combination. Examples of themonomers are 2,2,6,6-tetramethyl-4-piperidyl acrylate,2,2,6,6-tetramethyl-4-piperidyl methacrylate,1,2,2,6,6-pentamethyl-4-piperidyl acrylate,1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, and the like.

There is no specific limitation on the method for coating varioussubstrates with the primer containing the UV absorber as a copolymercomponent in the present invention. However, methods such as thosedescribed below may be employed: a method wherein a substrate is coatedwith a precopolymerized polymer solution, and dried; and a methodwherein a substrate is coated with a mixture of monomers, which arepolymerized thereon.

At the time of precopolymerization, any of polymerization methods suchas bulk polymerization, solution polymerization, suspensionpolymerization and emulsion polymerization may be employed. However,solution polymerization is preferable because a coating solution for theprimer is prepared at the time of coating the substrate with the primer.The polymer thus obtained is subjected to processing if necessary suchas solubilization, dilution and solvent replacement to obtain acopolymerized polymer solution for the primer. A substrate is coatedwith the solution, and dried to obtain a primer coating.

When a substrate is coated with the monomer mixture and the monomermixture is polymerized thereon, the substrate may be coated with themonomer mixture not having been processed or having been diluted with asolvent, and the mixture may be polymerized by irradiation with rayssuch as UV-rays, electron beams and γ-rays, or by heating with hot air,IR-rays, etc.

A substrate may also be coated with the polymer in which the UV absorberis copolymerized, or the monomer mixture, after diluting with a suitablesolvent. In the case of adding solvent, there is no specific limitationon the solvent. The solvent should be determined by considering themutual solubility with the copolymerized polymer, the adhesion thereofto the substrate, etc., and one or at least two solvents may beemployed.

Furthermore, various additives may also be added to the polymer whichforms these primer coatings and in which the UV absorber iscopolymerized, and the monomer mixture. UV absorbers, antioxidants andlight stabilizers other than those mentioned above may be added tofurther improve the weathering resistance. It is a preferable embodimentto use various surfactants for the purpose of improving the flow of theprimer during coating. Examples of the especially effective surfactantare block or graft copolymers of dimethylpolysiloxanes and alkyleneoxides, fluorine type surfactants, and the like.

Although the copolymerized polymer or monomer mixture may be applied toa substrate by ordinary coating operations, preferable examples of thecoating method are immersion coating, curtain coating, spin coating,brush coating, spray coating, roll coating, curtain flow coating, etc.

The thickness of the coating of the primer of the present inventionshould be determined by considering the properties of the surfacecoating to be formed on the primer coating and the adhesion of theprimer coating to the substrate. Though there is no specific limitationthereon, the thickness is 0.05 to 50 μm, preferably 0.1 to 10 μm.

Examples of the surface coating to be formed on the primer coating usedin the present invention are an acrylic coating, a silane type coating,an isocyanate type coating, a melamine type coating, an epoxy type hardcoat, etc., and there is no specific limitation thereon. However, anorganopolysiloxane hard coat is preferably used due to its weatheringresistance.

Typical examples of the composition to form the organopolysiloxane hardcoat are at least one organosilicon compound and/or its hydrolyzedproduct selected from the group consisting of organosilicon compoundsrepresented by the general formula (I) and their hydrolyzed products,and organosilicon compounds represented by the general formula (II) andtheir hydrolyzed products ##STR4## wherein R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸ andR¹⁹ are each an organic group having from 1 to 10 carbon atoms, X and Qare each a hydrolyzable group, a, c and e are each 0 or 1, b, d and fare each 0, 1 or 2, and Y is an organic group having from 2 to 40 carbonatoms.

Firstly, the organosilicon compounds represented by the general formula(I) and their hydrolyzed products are illustrated below.

R¹⁴ and R¹⁵ in the general formula (I) are each an organic group havingfrom 1 to 10 carbon atoms. Concrete examples of the organic group arehydrocarbon groups such as a methyl group, an ethyl group, a phenylgroup and a vinyl group, halogenated hydrocarbon groups such as achloropropyl group and a 3,3,3-trifluoropropyl group, epoxygroup-containing organic groups such as a γ-glycidoxypropyl group and aβ-(3,4-epoxycyclohexyl)ethyl group, (meth)acrylic group-containingorganic groups such as a γ-methacryloxypropyl group and aγ-acryloxypropyl group, other organic groups having various substituentgroups such as a mercapto group, a cyano group and an amino groups, andthe like. R¹⁴ and R¹⁵ may be the same as or different from each other.

Furthermore, X is not specifically restricted so long as it is ahydrolyzable functional group, that is, a silanol group is formed byhydrolysis of X. Concrete examples of X are alkoxy groups such as amethoxy group, an ethoxy group and a methoxyethoxy group, acyloxy groupssuch as an acetoxy group, halogeno groups such as a chloro group and abromo group, aryloxy groups such as a phenoxy group, and the like.

Furthermore, in the case of a+b being at least 2, at least one of R¹⁴and R¹⁵ is preferably a reactive organic group such as an epoxygroup-containing organic group and a (meth)acryloxy group-containingorganic group in view of the surface hardness.

Concrete typical examples of these organosilicon compounds aretrialkoxysilanes, triacyloxysilanes or triphenoxysilanes such asmethyltrimethoxysilane, methyltriethoxysilane,methyltrimethoxyethoxysilane, methyltriacetoxysilane,methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane,ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane,vinyltriacetoxysilane, vinyltrimethoxyethoxysilane,phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane,γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane,γ-chloropropyltriacetoxysilane, 3,3,3-trifluoropropyltrimethoxysilane,γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane,γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane,γ-mercaptopropyltrimethoxyethoxysilane, γ-mercaptopropyltriethoxysilane,N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane,β-cyanoethyltriethoxysilane, methyltriphenoxysilane,chloromethyltrimethoxysilane, chloromethyltriethoxysilane,glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane,α-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxy-silane,β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane,α-glycidoxypropyltrimethoxysilane, α-glycidoxypropyltriethoxysilane,β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyltriethoxysilane,γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane,γ-glycidoxypropyltripropxysilane, γ-glycidoxypropyltributoxysilane,γ-glycidoxypropyltrimethoxyethoxysilane,γ-glycidoxypropyltriphenoxysilane, α-glycidoxybutyltrimethoxysilane,α-glycidoxybutyltriethoxysilane, β-glycidoxybutyltrimethoxysilane,β-glycidoxybutyltriethoxysilane, γ-glycidoxybutyltrimethoxysilane,γ-glycidoxybutyltriethoxysilane, δ-glycidoxybutyltrimethoxysilane,δ-glycidoxybutyltriethoxysilane,(3,4-epoxycyclohexyl)methyltrimethoxysilane,(3,4-epoxycyclohexyl)methyltrimethoxysilane,β-(3,4-epoxycylcohexyl)ethyltrimethoxysilane,β-(3,4-epoxycyclohexyl)ethyltriethoxysilane,β-(3,4-epoxycyclohexyl)ethyltripropoxysilane,γ-(3,4-epoxycyclohexyl)ethyltributoxysilane,γ-(3,4-epoxycyclohexyl)ethyltrimethoxyethoxysilane,β-(3,4-epoxycyclohexyl)ethyltriphenoxysilane,γ-(3,4-epoxycyclohexyl)propyltrimethoxysilane,γ-(3,4-epoxycyclohexyl)propyltriethoxysilane,δ-(3,4-epoxycyclohexyl)butyltrimethoxysilane,δ-(3,4-epoxycyclohexyl)butyltriethoxysilane, or the hydrolyzed productsof trialkoxysilanes, triacyloxysilanes or triphenoxysilanes,dialkoxysilanes, diphenyoxysilanes or diacyloxysilanes such asdimethyldimethoxysilane, phenylmethyldimethoxysilane,dimethyldimethoxysilane, phenylmethyldiethoxysilane,γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane,dimethyldiacetoxysilane, γ-methacryloxypropylmethyldimethoxysilane,γ-methacryloxypropylmethyldiethoxysilane,γ-mercaptopropylmethyldimethoxysilane,γ-mercaptopropylmethyldiethoxysilane,γ-aminopropylmethyldimethoxy-silane, γ-aminopropylmethyldiethoxysilane,methylvinyldimethoxysilane, glycidoxymethylmethyldimethoxysilane,glycidoxymethylmethyldiethoxysilane,α-glycidoxyethylmethyldimethoxysilane,α-glycidoxyethylmethyldiethoxysilane,β-glycidoxyethylmethyldimethoxysilane,β-glycidoxyethylmethyldiethoxysilane,α-glycidoxypropylmethyldimethoxysilane,α-glycidoxypropylmethyldiethoxysilane,β-glycidoxypropylmethyldimethoxysilane,β-glycidoxypropylmethyldiethoxysilane,γ-glycidoxypropylmethyldimethoxysilane,γ-glycidoxypropylmethyldiethoxysilane,γ-glycidoxypropylmethyldipropoxysilane,γ-glycidoxypropylmethyldibutoxysilane,γ-glycidoxypropylmethyldimethoxyethoxysilane,γ-glycidoxypropylmethyldiphenoxysilane,γ-glycidoxypropylmethyldiacetoxysilane,γ-glycidoxypropylethyldimethoxysilane,γ-glycidoxypropylethyldiethoxysilane,γ-glycidoxypropylvinyldimethoxysilane,γ-glycidoxypropylvinyldiethoxysilane,γ-glycidoxypropylphenyldimethoxysilane andγ-glycidoxypropylphenyldiethoxysilane, and the hydrolyzed products ofdialkoxysilanes, diphenoxysilanes or diacyloxysilanes.

Next, the other organosilicon compounds represented by the generalformula (II) and their hydrolyzed products are illustrated below.

Examples of R¹⁶, R¹⁷, R¹⁸ and R¹⁹ in the general formula (II) are thesame as those of R¹⁴ and R¹⁵ in the general formula (I). Moreover,examples of Q are the same as those of X. Y is an organic group havingfrom 2 to 40 carbon atoms. That is, Y is a functional group contained inthe molecule through another two Si atoms each bonding to Y with Si--Cbonds, and there is no problem at all even when the functional groupcontains atoms other than carbon and hydrogen atoms, such as an oxygenatom and a nitrogen atom. The organic group may be chain-like or cyclicso long as it has from 2 to 40 carbon atoms. The presence of an oxygenatom, etc., in the form of an epoxy ring, etc., not only causes noproblem at all, but also preferably contributes as a functional groupduring curing.

Concrete examples of Y are as follows: ##STR5##

The use of an organosilicon compound containing an epoxy group orglycidoxy group as the organosilicon compound represented by the generalformula (I) or (II) is particularly suitable for imparting flexibility.Moreover, an organosilicon compound containing a vinyl group, a methylgroup, a phenyl group, etc., is preferably used for imparting weatheringresistance and water resistance. An alkoxy group or alkoxyalkoxy grouphaving from 1 to 4 carbon atoms is preferably used as X or Q in view ofthe curing rate and the facility of hydrolysis.

Of these organosilicon compounds and/or their hydrolyzed products, thehydrolyzed products are preferable from the standpoint of lowering thecuring temperature and promoting curing.

The hydrolyzed products are prepared by adding pure water, or an acidicaqueous solution of an acid such as hydrochloric acid, acetic acid orsulfuric acid to the organosilicon compounds and stirring the mixture.Furthermore, it becomes readily possible to control the degree ofhydrolysis by adjusting the addition amount of pure water or the acidicaqueous solution. Pure water or the acidic aqueous solution is added atthe time of hydrolysis particularly preferably in a molar ratio of purewater or the acidic aqueous solution to X or Q in the general formula(I) or (II) of at least 1 to up to 3 from the standpoint of thepromotion of curing.

Since alcohol, etc., is formed during hydrolysis, hydrolysis may becarried out without a solvent. Hydrolysis may also be carried out aftermixing the organosilicon compound with a solvent for the purpose of moreuniformly carrying out hydrolysis. Moreover, the hydrolyzed product maybe used after removing a suitable amount of the alcohol, etc., byheating and/or reducing the pressure, and, thereafter, a suitablesolvent may also be added to the hydrolyzed product, the selection ofthese procedures depending on the application thereof.

Examples of the solvent are alcohols, esters, ethers, ketones,halogenated hydrocarbons, aromatic hydrocarbons such as toluene andxylene and solvents such as N,N-dimethylformaide. These solvents mayalso be optionally used as a solvent mixture of at least two of them.

It is naturally possible that the hydrolysis reaction mixture should beheated to a temperature of at least room temperature to acceleratehydrolysis and further promote reactions such as precondensation, andthat hydrolysis should also be carried out by lowering the hydrolysistemperature to room temperature to inhibit precondensation, theprocedures depending on the application of the hydrolyzed product.

Furthermore, a particulate inorganic oxide is preferably used as aningredient for improving the hardness of the surface coating. There isno specific limitation on the inorganic oxide so long as it does notimpair the transparency of the coating in a coated state and achieve theapplication of its use. However, particularly preferable examples arecolloidally dispersed sols from the standpoint of processability andimparting transparency. More concrete examples thereof are a silica sol,a titanium oxide sol, a cerium oxide sol, a zirconia sol, an antimonyoxide sol, an alumina sol, etc. Further, a magnesium fluoride sol can beused for the same purpose. Although the addition amount of theparticulate inorganic oxide is not particularly restricted, to obtainmore significant effects, it is preferable that the particulateinorganic oxide should be contained in the cured coating in an amount offrom at least 5% by weight to up to 80% by weight. That is, evidenteffects of the addition cannot be recognized when the amount is lessthan 5% by weight, and the resultant coating tends to exhibitinsufficient adhesion to the primer coating, crack formation therewithinand the lowering of impact resistance thereof when the amount exceeds80% by weight.

Although a particulate inorganic oxide having an average particle sizeof from 1 to 200 mμ is usually used, one having an average particle sizeof from 5 to 100 mμ is preferably used.

When the average particle size exceeds 200 mμ, the resultant coating hasreduced transparency and exhibits a marked haze, and thick coatingformation becomes difficult. When the average particle size is less than1 mμ, the coating exhibits poor stability, and the reproducibility ofthe coating formation becomes poor. The addition of various surfactantsand amines to improve the dispersibility of the fine particles causes noproblem. Moreover, the use of at least two of the particulate inorganicoxides in combination causes no problem.

Furthermore, non-glare properties may also be imparted to the surfacecoating. Concrete examples of the method include the use of the silicasol aggregate and the addition of silica fine particles.

Still furthermore, a variety of surfactants may also be used for thecoating composition for forming the surface coating to improve the flowof the coating composition during coating. It is particularly effectiveto use a block or graft copolymer of dimethylpolysiloxane and alkyleneoxide, a fluorine type surfactant, etc.

An UV absorber may also be added to further improve the weatheringresistance, and an antioxidant may also be added to improve the thermaldeterioration resistance.

Furthermore, a variety of inorganic compounds, etc., may also be addedto the compositions for the surface coating so long as thecoating-formation properties, transparency, etc., are not markedlyreduced. The use of these additives in combination can improve theadhesion between the surface coating and the substrate, and theproperties of the surface coating, such as chemical resistance, surfacehardness, durability and dyeing properties. Examples of the inorganicmaterials which can be added as mentioned above are metal alkoxidesrepresented by the following general formula [III], and a variety ofchelate compounds and/or their hydrolyzed products:

    M(OQ).sub.m                                                [III]

wherein Q is an alkyl group, an acyl group or alkoxyalkyl group, m is anumerical value equal to the number of electric charges of metal M, andM is silicon, titanium, zircon, antimony, tantalum, germanium,aluminium, etc.

At the time of forming the surface coating in the present invention,various curing agents may be used to make it possible to promote curing,or cure at low temperature. Those curing agents which are used forcuring various epoxy resins or various organosilicon resins, etc., maybe used as the curing agents.

Concrete examples of these curing agents are various organic acids andtheir acid anhydrides, nitrogen-containing organic compounds, variousmetal complexes, metal alkoxides, alkali metal salts of organiccarboxylic acids, various salts such as carbonates, radicalpolymerization initiators such as a peroxide andazobis(isobutyronitrile), and the like. A mixture of at least two ofthese curing agents may also be used. Among these curing agents,aluminum chelate compounds as described below are particularly usefulfor satisfying the objects of the present invention, from the standpointof stabilizing the coating compositions and preventing the coloration ofthe coatings after their formation. That is, use can be made of aluminumchelate compounds represented by the general formula AlT_(r) Z_(3-r)wherein T is OL (wherein L is a lower alkyl group), Z is at least onemember selected from the group consisting of ligands derived fromcompounds represented by the general formula M¹ COCH₂ COM² (wherein M¹and M² are each a lower alkyl group) and ligands derived from compoundsrepresented by the general formula M³ COCH₂ COM⁴ (wherein M³ and M⁴ areeach a lower alkyl group), and r is 0, 1 or 2. Of aluminum chelatecompounds represented by the general formula AlT_(r) Z_(3-r),particularly preferable are acetylacetonatoaluminum,monoacetylacetonatobis(ethylacetoacetato)aluminum,di-n-butoxide-monoethylacetoacetatoaluminum,di-isopropoxide-monomethylacetoacetatoaluminum, etc., in view of thesolubility in the composition, the stability, the effects as curingcatalysts, etc. These compounds may also be used as a mixture of atleast two of them.

Methods used in conventional coating operations may be applied to themethod for coating the compositions for the surface coating. Preferableexamples of the coating method are immersion coating, curtain coating,spin coating, brush coating, spray coating, roll coating, curtain flowcoating, etc.

The coating composition with which a substrate has been coated isgenerally cured by heating and drying.

Heating may be carried out by hot air, IR-rays, etc. Although theheating temperature should be determined by the substrate and thecoating composition to be used, the temperature is usually from roomtemperature to 250° C., more preferably from 35° to 200° C. A heatingtemperature lower than that mentioned above may result in insufficientcuring or drying. A heating temperature higher than that mentioned abovecauses thermal decomposition, crack formation, etc., and tends to causeproblems such as yellow discoloration.

Though the thickness of the surface coating in the 30 present inventionis not specifically restricted, it is preferably from 0.1 to 200 μm,particularly preferably from 0.4 to 100 μm in view of the maintenance ofthe adhesion strength, the hardness, the surface gloss, etc.

Furthermore, the substrate or substrate provided with a primer may alsobe subjected to various chemical and physical treatments to furtherimprove the adhesion and the wettability between the substrate and theprimer coating, or the primer coating and the surface coating.Preferable examples of the chemical treatment are immersion in hotwater, immersion in a solvent, oxidation and reduction treatment,treatment with an acid or alkali, etc. Preferable examples of thephysical treatment are plasma treatment, corona discharge treatment,UV-ray irradiation, etc.

The primer coating or surface coating of the invention may be coloredwith dyes or pigments without impairing their properties. Colorationproduces very high added values.

Though the substrate for the primer of the present invention is notspecifically restricted, glass, plastics, etc., are preferable becausethe primer is a liquid coating material. A plastic substrate is oftensubjected to yellow discoloration or peeling of the surface coating byUV-ray irradiation when used outdoors. Accordingly, the primer of thepresent invention is particularly preferably used. Preferable examplesof the plastic substrate are a polymethyl methacrylate and itscopolymer, a polycarbonate, a poly[diethylene glycol bis(allylcarbonate)] (trade name of CR-39), a polyester, particularly apolyethylene terephthalate, an unsaturated polyester, anacrylonitrile-styrene copolymer, a polyvinyl chloride, a polyurethane,an epoxy resin, and the like. The primer can also be favorably appliedto the above-mentioned glass or plastic substrates coated with variouscoating materials.

There is no specific limitation on the uses of the primer of theinvention so long as it is used in fields requiring weatheringresistance. The primer is not only useful for construction materials,optical uses and agricultural uses but also it may be developed into avariety of applications.

The present invention is illustrated below with reference to examples,but it should be construed that the invention is in no way limited tothose examples.

EXAMPLE 1

(1) Preparation of a primer composition

A four-necked flask equipped with a dropping funnel, a nitrogen inlettube, a condenser and a stirrer was prepared. In the flask was placed 15g of toluene, and the toluene was held at 50° C. To the toluene wasadded, by dropping with a dropping funnel over a period of one hour anda half, a mixture of 15 g of toluene, 63 g of methyl methacrylate, 7 gof a benzophenone type UV absorber having an unsaturated double bond andrepresented by the formula ##STR6## and 0.1 g of2,2'-azobis(4-methoxy-2,4'-dimethylvaleronitrile) as a polymerizationinitiator. The reaction mixture was then stirred for 4 hours at aconstant temperature to obtain a copolymerized polymer solution.

To 43.7 g of the copolymerized polymer solution were added 10 g oftoluene, 31.5 g of methyl isobutyl ketone, 15.0 g of benzyl alcohol,60.0 g of n-butanol and 0.08 g of SH-190 (trade name of a siliconesurfactant manufactured by Dow Corning Toray Silicone Co., Ltd.), andthe mixture was stirred until it became homogeneous.

(2) Preparation of an organopolysiloxane hard coat composition

(a) To 263.7 g of vinyltriethoxysilane was added 19.8 g of acetic acid.The mixture solution was held at 10° C. with stirring, and 74.7 g of0.05N HCl was added thereto to obtain a hydrolyzed product ofvinyltriethoxysilane.

(b) To 378.0 g of methyltrimethoxysilane was added 28.8 g of aceticacid. The mixture solution was held at 10° C., and 149.4 g of 0.01N HClwas added thereto to obtain a hydrolyzed product ofmethyltrimethoxysilane.

(c) The hydrolyzed product of vinyltriethoxysilane in an amount of 352.6g obtained in (a) and the hydrolyzed product of methyltrimethoxysilanein an amount of 547.4 g obtained in (b) were mixed by stirring. To themixture were further added 2 g of sodium acetate, 80 g of xylene, 20 gof butyl acetate and 1.5 g of SRX-298 (trade name of a siliconesurfactant manufactured by Dow Corning Toray Silicone Co., Ltd. ), andthe mixture was stirred, until it became homogeneous, to obtain a hardcoat composition.

(3) Coating and curing

A polycarbonate plate was used as a plastic substrate. The plate wascleaned, dried, and coated with the primer composition prepared in (1)by immersion coating under the condition of a pulling speed of 20cm/min. The coated plate was cured by heating for an hour with a hot airdrier at 93° C. The plate coated with the primer composition was furthercoated with the hard coat composition prepared in (2) under the samecondition mentioned above. The coated plate was cured by heating for 2hours with a hot air drier at 140° C.

(4) Test results

The plastic plate having coatings thus obtained was evaluated by thefollowing test procedures. The results thus obtained are shown in Table1.

(a) Appearance

The transparency, the coloring properties and the cracks of the coatingfilm were visually observed.

(b) Hardness

The coatings were rubbed with #0000 steel wool, and the degree of flawformation was judged. The judging standard is as follows: A: almost noflaws are formed even when the coatings are strongly rubbed; and B:slight flaws are formed when the coatings are strongly rubbed.

(c) Adhesion

On the coatings were formed 100 cross hatches each 1 square millimeter.A cellophane adhesive tape (trade name of Cellophane Tape manufacturedby Nichiban K.K.) was firmly applied to the coatings, and quickly peeledoff in the direction making an angle of 90° with the applied portion ofthe tape, and the peel of the coatings was examined.

(d) Coloring properties

The degree of yellow discoloration, YI, was measured using a colorcomputer (manufactured by Suga Shikenki K.K.).

(e) Weathering resistance

Weathering test was conducted on the coatings for 300 hours using Q.U.V.(manufactured by Q-panel Co., Ltd.) as a weatherometer, and (c) and (d)described above were measured.

EXAMPLE 2

(1) Preparation of a primer composition

A four-necked flask equipped with a dropping funnel, a nitrogen inlettube, a condenser and a stirrer was prepared. In the flask was placed 15g of toluene, and the toluene was held at 50° C. To the toluene wasadded, by dropping with a dropping funnel over a period of one hour anda half, a mixture of 15 g of toluene, 66.5 g of methyl methacrylate, 3.5g of the compound represented by the formula (A) and having been used inExample 1 as a benzophenone type UV absorber having an unsaturateddouble bond and 0.1 g of2,2'-azobis(4-methoxy-2,4'-dimethylvaleronitrile) as a polymerizationinitiator. The reaction mixture was then stirred for 4 hours at aconstant temperature to obtain a copolymerized polymer solution.

Various solvents were added to the copolymer solution in the same manneras in Example 1 to obtain a primer composition.

(2) Coating and curing

A polycarbonate plate was used as a plastic substrate. The plate wascleaned, dried, and coated with the primer composition prepared in (1)by immersion coating. The procedures of Example 1 were repeated withregard to the coating and drying conditions, and coating and curing ofthe surface hard coat.

(3) Test results

The plastic plate having the coatings thus obtained was evaluated in thesame manner as in Example 1. The results thus obtained are shown inTable 1.

EXAMPLE 3

(1) Preparation of a primer composition

A four-necked flask equipped with a dropping funnel, a nitrogen inlettube, a condenser and a stirrer was prepared. In the flask was placed 15g of toluene, and the toluene was held at 50° C. To the toluene wasadded, by dropping with a dropping funnel over a period of one hour anda half, a mixture of 15 g of toluene, 66.5 g of methyl methacrylate, 3.5g of a compound represented by the formula (B) ##STR7## as abenzotriazole type UV absorber having an unsaturated double bond and 0.1g of 2,2'-azobis(4-methoxy-2,4'-dimethylvaleronitrile) as apolymerization initiator. The reaction mixture was then stirred for 4hours at a constant temperature to obtain a copolymerized polymersolution.

Various solvents were added to the copolymerized polymer solution in thesame manner as in Example 1 to obtain a primer composition.

(2) Coating and curing

A polycarbonate plate was used as a plastic substrate. The plate wascleaned, dried, and coated with the primer composition prepared in (1)by immersion 30 coating. The procedures of Example 1 were repeated withregard to the coating and drying conditions, and coating and curing ofthe surface hard coat.

(3) Test results

The plastic plate having the coatings thus obtained were evaluated inthe same manner as in Example 1. The results thus obtained are shown inTable 1.

EXAMPLE 4

(1) Preparation of a primer composition

A four-necked flask equipped with a dropping funnel, a nitrogen inlettube, a condenser and a stirrer was prepared. In the flask was placed 15g of toluene, and the toluene was held at 50° C. To the toluene wasadded, by dropping with a dropping funnel over a period of one hour anda half, a mixture of 15 g of toluene, 60 g of methyl methacrylate, 3.5 gof a compound represented by the general formula (A) as a benzophenonetype UV absorber having an unsaturated double bond and used in Example1, 3.5 g of a hindered amine methacrylate compound having the structure##STR8## as a light stabilizer and 0.1 g of2,2'-azobis(4-methoxy-2,4'-dimethylvaleronitrile) as a polymerizationinitiator. The reaction mixture was then stirred for 4 hours at aconstant temperature to obtain a copolymerized polymer solution.

Various solvents were added to the copolymer solution in the same manneras in Example 1 to obtain a primer composition.

(2) Coating and curing

A polycarbonate plate was used as a plastic substrate. The plate wascleaned, dried, and coated with the primer composition prepared in (1)by immersion coating. The procedures of Example 1 were repeated withregard to the coating and drying conditions, and coating and curing ofthe surface hard coat film.

(3) Test results

The plastic plate having the coatings thus obtained was evaluated in thesame manner as in Example 1. The results thus obtained are shown inTable 1.

Comparative Example 1

(1) Preparation of a primer composition

A four-necked flask equipped with a dropping funnel, a nitrogen inlettube, a condenser and a stirrer was prepared. In the flask was placed 15g of toluene, and the toluene was held at 50° C. To the toluene wasadded, by dropping with a dropping funnel over a period of one hour anda half, a mixture of 15 g of toluene, 70 g of methyl methacrylate and0.1 g of 2,2'-azobis(4-methoxy-2,4'-dimethylvaleronitrile) as apolymerization initiator. The reaction mixture was then stirred for 4hours at a constant temperature to obtain a polymer solution.

Various solvents were added to the polymer solution in the same manneras in Example 1 to obtain a primer composition.

(2) Coating and curing

A polycarbonate plate was used as a plastic substrate. The plate wascleaned, dried, and coated with the primer composition prepared in (1)by immersion coating. The procedures of Example 1 were repeated withregard to the coating and drying conditions, and coating and curing ofthe surface hard coat.

(3) Test results

The plastic plate having coatings thus obtained was evaluated in thesame manner as in Example 1. The results thus obtained are shown inTable 1.

Comparative Example 2

(1) Preparation of a primer composition

To the primer composition obtained in Comparative Example 1 was added 5g of 2-hydroxybenzophenone as an UV absorber, and the mixture was 35stirred until it became uniform to obtain a primer composition.

(2) Coating and curing

A polycarbonate plate was used as a plastic substrate. The plate wascleaned, dried, and coated with the primer composition prepared in (1)by immersion coating. The procedures of Example 1 were repeated withregard to the coating and drying conditions, and coating and curing ofthe surface hard coat.

(3) Test results

The plastic plate having coatings thus obtained was evaluated in thesame manner as in Example 1. The results thus obtained are shown inTable 1.

                  TABLE 1                                                         ______________________________________                                        Properties   Ex. 1  Ex. 2  Ex. 3                                                                              Ex. 4                                                                              C.E. 1                                                                              C.E. 2                             ______________________________________                                        Appearance   good   good   good good good  good                               Hardness     A      A      A    A    A     A                                  Adhesion     good   good   good good good  good                               Coloring Properties                                                                        -0.1   0.0    -0.1 0.0  -0.2  0.1                                ΔYI                                                                     Weathering-resistant                                                                       good   good   good good no    no                                 adhesion                             good  good                               Weathering-resistant                                                                       -0.1   0.3    -0.1 0.0   7.8  1.5                                coloring properties                                                           ______________________________________                                         Note: C.E. = Comparative Example                                         

INDUSTRIAL APPLICABILITY

The present invention can provide a primer which improves theweathering-resistant adhesion between a substrate and a coating used forimproving surface properties of various substrates, such as surfacehardness, scuff resistance, wear resistance and surface gloss, and whichfurther inhibits the weathering resistance 20 deterioration ofsubstrates, and a multilayer coated article having a coating of theprimer.

We claim:
 1. A primer comprising copolymer units of a benzophenone UVabsorber represented by the general formula ##STR9## wherein at leastone of R¹, R², R³ and R⁴ is an organic group having an unsaturateddouble bond, and the others are each a substituent group selected fromthe group consisting of an alkyl group, an aralkyl group, an aryl group,an aralkoxy group, an allyloxy group, a halogeno group, a sulfonic acidgroup, an ester of a sulfonic acid group, a carboxylic acid group, anester of a carboxylic acid group, a phosphoric acid group and an esterof a phosphoric acid group.
 2. A primer comprising copolymer units of abenzotriazole UV absorber represented by the general formula ##STR10##wherein at least one of R⁵, R⁶ and R⁷ is an organic group having anunsaturated double bond, and the others are each a substituent groupselected from the group consisting of a hydrogen atom, an alkyl group,an alkenyl group, an aralkyl group, an aryl group, an alkoxy group, anaralkoxy group, an allyloxy group, a hydroxy group, a halogeno group, asulfonic acid group, an ester of a sulfonic acid group, a carboxylicacid group, an ester of a carboxylic acid group, a phosphoric acid groupand an ester of a phosphoric acid group.
 3. A primer comprisingcopolymer units of a phenyl benzoate UV absorber represented by thegeneral formula ##STR11## wherein at least one of R⁸ ˜R¹³ is an organicgroup having an unsaturated double bond, and the others are each asubstituent group selected from the group consisting of a hydrogen atom,an alkyl group, an alkenyl group, an aralkyl group, an aryl group, analkoxy group, an aralkoxy group, an allyloxy group, a hydroxy group, ahalogeno group, a sulfonic acid group, an ester of a sulfonic acidgroup, a carboxylic acid group, an ester of a carboxylic acid group, aphosphoric acid group and an ester of a phosphoric acid group.
 4. Aprimer as claimed in claims 1 to 3, wherein the group having anunsaturated double bond is selected from the group consisting of a vinylgroup, an allyl group, a vinylene group and a (meth)acryloyl group.
 5. Aprimer as claimed in claims 1 to 3 wherein a monomer copolymerized withthe UV absorber is selected from the group consisting of (meth)acrylicacid, a (meth)acrylate, a (meth)acrylamide and a vinyl group-containingmonomer.
 6. A primer as claimed in claim 5, wherein the copolymerizationproportion of the UV absorber in the copolymer is from 0.1 to 20% byweight based on the entire amount of the monomer.
 7. A primer as claimedin claim 5 wherein said (meth)acrylate is selected from the groupconsisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl(meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl(meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, heptyl(meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, dodecyl(meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate,2-hydroxy-propyl (meth)acrylate, glycidyl (meth)acrylate,N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycoldi(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,4-butanedioldi(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycoldi(meth)acrylate, trimethylolpropane di(meth)acrylate,trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate,pentaerythritol tri(meth)acrylate and pentaerythritoltetra(meth)acrylate.
 8. A primer as claimed in claims 1 to 3, wherein amonomer copolymerized with the UV absorber comprises an antioxidant or alight stabilizer having an unsaturated double bond.
 9. A multilayercoated article comprising a substrate, a primer coating as defined inclaims 1 to 3 and a coat on the primer coating.
 10. A multilayer coatedarticle as claimed in claim 9, wherein the coat is an organopolysiloxanecoat.
 11. A multilayer coated article as claimed in claim 10, whereinthe organopolysiloxane coat is formed by using at least one memberselected from the group consisting of organosilicon compoundsrepresented by the following general formula (I) or (II) and hydrolyzedproducts thereof: ##STR12## wherein R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸ and R¹⁹ areeach an organic group having from 1 to 10 carbon atoms, X and Q are eacha hydrolyzable group, a, c and e are each 0 or 1, b, d and f are each 0,1 or 2, and Y is an organic group having from 2 to 40 carbon atoms. 12.A multilayer coated article as claimed in claim 10, wherein theorganopolysiloxane coat comprises a particulate inorganic oxide.
 13. Amultilayer coated article as claimed in claim 9, wherein the substrateis selected from the group consisting of a polycarbonate, a polymethylmethacrylate, a copolymer comprising copolymerized units of a methylmethacrylate, a poly[diethylene glycol bis(allyl carbonate)], apolyester, an acrylonitrile-styrene copolymer, a polyvinyl chloride, apolyurethane and an epoxy resin.
 14. A multilayer coated article asclaimed in claim 9, wherein the proportion of the copolymerized units ofthe UV absorber is from 0.1 to 20% by weight based on the entire amountof monomers.
 15. A multilayer coated article as claimed in claim 9,wherein a monomer copolymerized with the UV absorber comprises anantioxidant or a light stabilizer having an unsaturated double bond. 16.A primer comprising copolymer units of a benzophenone UV absorberrepresented by the general formula ##STR13## wherein two or more of R¹,R², R³ and R⁴ are an organic group having an unsaturated double bond,and the others are each a substituent group selected from the groupconsisting of a hydrogen atom, an alkyl group, an alkenyl group, anaralkyl group, an aryl group, an alkoxy group, an aralkoxy group, anallyloxy group, a hydroxy group, a halogeno group, a sulfonic acidgroup, an ester of a sulfonic acid group, a carboxylic acid group, anester of a carboxylic acid group, a phosphoric acid group and an esterof a phosphoric acid group.